XMM-Newton and Chandra Observations of Neutron Stars and Cataclysmic Variables in the Globular Cluster NGC 2808

摘要

We report on XMM-Newton and Chandra observations of the globular cluster NGC 2808.We detect one quiescent low mass X-ray binary of the 3±1 expected, if these systems are formed through encounters, and we show evidence for the presence of 20±10 bright cataclysmic variables in the core with a luminosity above 4x1031 erg s-1. We also review the specific nature of cataclysmic variables in globular clusters with reference to recent VLT/FORS1 observations of a cataclysmic variable in M 22.